Roadway for decelerating and/or accelerating a vehicle including an aircraft

ABSTRACT

A roadway upon which a vehicle travels is provided in which the vehicle is decelerated. The roadway includes: a movable surface extending in a direction of the vehicle&#39;s travel; and a potential energy storage mechanism operatively connected to the movable surface for converting a kinetic energy of the vehicle into potential energy upon movement of the movable surface thereby slowing the vehicle. Also provided is a roadway upon which a wheeled vehicle travels in which the vehicle is accelerated. The roadway includes: a movable surface extending in a direction of the vehicle&#39;s travel; and a potential energy transfer mechanism operatively connected to the movable surface for transferring a stored potential energy associated with the movable surface into kinetic energy upon movement of the movable surface thereby propelling the vehicle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to moving objects and devicesfor use therewith; and more particularly, to methods and devices foraccelerating and decelerating moving vehicles.

2. Prior Art

Along many highways, exits are provided for runaway trucks or othertypes of vehicles. Once a vehicle takes such an exit, it enters astretch of a road that is filled with relatively fine sand of anappropriate depth. As the runaway vehicle enters the sand-filled portionof the road, it quickly begins to decelerate and slow down and after arelatively short distance it comes to rest. The deceleration of thevehicle is caused primarily by the process of “sinking” the vehicletires into the sand, and forcing it to continuously climb the height ofthe sand in front of it, i.e., a height equal to the sinking depth ofthe tire. The kinetic energy of the vehicle is absorbed primarily by thefriction forces generated within the displacing sand. This process isfairly similar to an uphill travel of a vehicle, which would deceleratea non-powered vehicle and eventually bring it to rest. The amount ofdeceleration, i.e., the rate of slow-down, is dependent on the uphillslope. For the case of a sand-filled road, the amount of decelerationthat can be achieved is dependent on the depth of the sand and themechanical characteristics in terms of the amount of resistance that itcan provide to its displacement by the tires.

As the vehicle travels along the sand-filled road, the vehicle usuallyexperiences a fairly bumpy ride, since the sand cannot be made andmaintained perfectly flat and perfectly homogeneous or protected fromcontaminants carried by the wind and rain and also by an unevenabsorption of moisture. Another major disadvantage of the sand is thatdue to the relatively small friction that it provides between the tireand the roadway, the tires can easily skid sideways and slip,particularly if the driver attempts to use the brakes, and the vehiclemay easily be rendered minimally controllable while slowing down. As aresult, accidents, such as overturning and jackknifing, can occur whilethe vehicle is being brought to rest. The skidding, slipping and partialloss of control becomes increasingly more probable with increasedinitial speed of the vehicle as it enters the stretch of sand-filledroad.

In addition, a depth of sand that is most appropriate for a certainvehicle weight, number of tires, and/or tire size may not be appropriatefor other vehicles having a significantly different weight, number oftires, and/or tire size. For example, a road with a depth of sand thatis appropriate for a heavy truck will decelerate a light vehicle toofast and can therefore result in injury to the passengers due to therapid deceleration and/or most likely due to the vehicle loss ofcontrol. The optimal depth of the sand is also dependent on the initialspeed of the vehicle. If a vehicle enters the sand-filled road with arelatively slow speed, then it would be best for the depth of sand to berelatively small, so that the vehicle is brought to stop as slowly asthe length of the sand-filled road allows. Other factors also contributeto the optimal design of such sand-filled roads such as the weight ofthe vehicle, the number and size of the tires, etc. In short, to achievean optimal condition, a sand-filled road has to be tuned to the type ofthe vehicle, its entering weight and initial velocity. In addition, theroad and sand conditions have to be regularly monitored and maintained.Such conditions cannot obviously be met for roads that are constructedfor general use and are subject to various environmental conditions.Such sand-filled roads are in use in numerous highways and areparticularly located where the downward slope of the road is high andheavier vehicles such as trucks are prone to run away and are used asthe means of last resort.

Such sand-filled roads are not, however, suitable for fast movingvehicles such as airplanes. For the case of airplanes, other issues mayalso arise. For example, the load on each tire is usually much largerthan road vehicles; the relative distance between the tires may besmaller than those of road vehicles, thereby rendering them moreuncontrollable; the center of mass of the plane may be higher than thatof road vehicles, thereby making them more prone to tipping over; etc.In addition, and particularly for fast moving planes, the load appliedto the tires keep varying due to the suspensions and the lift action,and therefore may cause a ripple to be formed on the surface of thesand-filled road, thereby making the ride even more bumpy anduncontrollable. In addition, the sand-filled section of the runway needsto be re-leveled after each use. In short, sand-filled roads are notappropriate and practical for fast moving vehicles in general and forairplanes in particular.

To overcome the aforementioned shortcomings for airplanes, runwaysegments have been added to the end of test runways that are constructedwith a special type of concrete that collapses in a more or lesscontrolled manner under the load of the airplane tire. Such runwaysegments solve some of the aforementioned problems of sand-filledroadways. However, such runway segments leave some of the majoraforementioned problems unsolved and they even create some new problemsand hazards. For example, the problem of lack of control is onlypartially solved by reducing the skidding potential caused by the sand.However, the collapsed concrete tends to constrain the tire to travel,more or less, in the generated “groove,” making it difficult for theplane to maneuver (turn) sideways due to the resistance that theuncrushed “concrete wall” provides against the tire as it attempts toturn sideways. In addition, the concrete material cannot be formed suchthat it is sufficiently homogeneous to prevent bumpy rides. In addition,the collapsible concrete runway can only be optimally formulated andconstructed for a certain airplane with a certain total weight andcertain initial velocity as it reaches the collapsible segment of therunway.

Furthermore, once the collapsible segment of the runway is used by a“runaway” plane during landing or takeoff, the damaged segment has to berepaired before the runway can be opened to traffic. Otherwise, thedamaged segment would pose a hazardous condition for the next runawayplane or even for a plane that could have stopped if a regular runwaysegment was present in place of the collapsible segment. In addition,while the repair crew is repairing the damage, any takeoff or landingwould pose a hazardous condition for the repair crew and the plane. Theuse of the runway must therefore wait for the completion of the repairs,including the time required for the proper setting of the added orreplaced sections of the concrete and inspection of the final conditionof the runway. In short, the operation of the airport must besignificantly curtailed for a significant length of time and if theairport has only one runway, the entire operation of the airport has tobe suspended until the damaged sections of the collapsible runway hasbeen repaired. In short, such collapsible runway segments have majortechnical difficulties for safe operation and even those technicalproblems are one day solved, they are still effectively impractical dueto the required relatively long periods of closure after each use andthe related economical costs involved.

A need therefore exits for reusable runways and driveways that can slowdown or bring to stop a “runaway” vehicle. For high-speed approaches,particularly for airplanes, it is also essential that the ride be assmooth as possible and that the vehicle stays fully controllable duringthe entire time it is being decelerated. It is also highly desirablethat the runway or driveway parameters be readily adjustable tooptimally match the type, weight and initial speed of the vehicle. Suchadaptable runway segments are particularly important for planes for theaforementioned reasons and in practice, the parameters of the runwaysegment can be readily adjusted by the air traffic controller or even bythe pilot since all the required information about the plane and itsflight conditions is known prior to landing and takeoff. The informationmay even be automatically transmitted from the plane by a wireless meansto a central processor. In addition, if the plane is experiencing sometype of malfunction or is damaged, the runway segment may be adjustedfor optimal performance with each specific condition. Such changes inthe runway parameters may be achieved manually or automatically beforethe plane reaches the runway segment or even as it is traveling alongthe runway.

Such runway segments may even be placed along the entire length or aportion of the runway (or other road surface) to routinely assist in thedeceleration of aircraft (or other vehicles), thereby reducing theirtire and brake wear. The equipped runway segments may also be keptinactive, thereby acting as a regular (solid) segment of the roadwaysurfaces and be activated only when needed, such as in an emergency.

SUMMARY OF THE INVENTION

Hereinafter, such runway or driveway segments are referred to as“reusable and adaptive runways” (RAR) without intending to limit theirapplications to airplanes or for their deceleration. Those skilled inthe art will appreciate that the devices and methods of the presentinvention, although having particular utility for decelerating aircraft,can be used for any type of vehicle and for deceleration as well asacceleration thereof. For example, the RAR can be used on portions of ahighway, such as on segments of the shoulders of the roadway foremergency stops or on exit ramps to assist in decelerating vehicles,particularly those that are traveling at dangerously high speeds, asthey leave the highway. Thus, the RAR can be used regularly in suchsituations to decrease the length of exit ramps, or can be used inconnection with a detection system and only employed where a dangerouscondition is detected. In the latter, for example, a detection systemcan detect a large truck traveling too fast for a particular exit rampand as a result automatically activate the RAR to slow the truck. Ofcourse, a manual operator can also activate the RAR, which can be thedriver of the truck.

During landing, the kinetic energy of the airplane due to its mass andspeed is transformed into potential energy stored in elastic or othersimilar types of elements of the RAR. A portion of the kinetic energy,preferably a small portion, is transformed into other types of energiessuch as heat. The stored potential energy may later be used toaccelerate the airplane forward during takeoff, thereby reducing theamount of energy required to bring the plane to its takeoff speed,and/or shorten the length of the runway needed for takeoff.

The primary objective of the present invention is to provide reusableand adaptive runways (RAR) that can be used safely by high-speedvehicles in general and airplanes in particular. To this end, thedisclosed RAR has one or more of the following characteristics:

1. The RAR is preferably reusable, in the sense that none of itscomponents are permanently damaged after each use and can be broughtback to its usable condition within a very short period of timeautomatically or by an operator.

2. An operator is preferably able to set and control the parameters ofthe runway to optimally match the type, weight, initial speed and otherappropriate traveling conditions of the vehicle as possible.

3. As the vehicle travels along the RAR and its characteristics andtraveling conditions are measured more accurately or is varied, theparameters of the RAR can be preferably adjusted accordingly for moreoptimal operation of the RAR. For example, if the vehicle brakes arestill operational, then the RAR could be set to only assist the brakesin stopping or slowing down the vehicle.

4. The runway may preferably be equipped with any one of the availablemeans of determining the entering speed of the vehicle, its weight andby means of a pattern recognition software, the type of vehicle and anyvisible structural damage for optimally setting the parameters of theRAR automatically or by an operator (which may be the driver or thepilot).

5. The runway may be equipped with the communications equipmentnecessary to receive the information indicated in the previous itemdirectly from the vehicle for use for optimally setting the parametersof the RAR automatically or by an operator (which may be the driver orthe pilot). The RAR controller may combine the information received fromthe vehicle with information collected by the runway sensoryinstrumentation (as described in the previous item) to check for anydiscrepancy or added information and base its decision for optimalsetting of the RAR parameters on the total collected data for maximumreliability.

6. The RAR provides a safe process for slowing down the vehicle or forbringing it to a stop in the sense that it does not reduce the frictionbetween the tire and the runway surface and it does not tend to forcethe tire to follow a given path such as the impressed path generated inthe collapsible concrete or sand, both of which can readily lead toskidding, slippage and/or loss of control by the pilot or driver.

7. The operator of the vehicle or the runway or an appropriatelycomputerized automated control unit is preferably able to optimally setthe parameters of the RAR for bringing the vehicle to a complete stop orto a reduced speed over a desired distance of travel along the RAR.

8. The RAR system can be set to operate automatically, i.e., becomeoperational for each and every landing and takeoff, thereby providing afailsafe mechanism for the operation of runways.

9. The entire or a major segment of the runway may be constructed as aRAR unit, thereby allowing planes to use them to bring them to a stopwith minimal or less use of their brakes, thereby minimizing brakingsystem, tire, and runway wear.

Another objective of the present invention is to provide the means toreduce the required length of runways for landing airplanes, whilereducing stress on the structure of the airplane during hard braking,reducing tire wear, reducing brake wear, and making the airplane morecontrollable during its deceleration. Deceleration by braking is theresult of the work done by the friction force between the tire and theroad surface. This friction force tends to tip over the vehicle since itacts at a point away (below) the center of mass of the vehicle. In thisregard, an advantage of the RAR runways is that it can deceleratevehicles without the tendency of tipping them over.

Another objective of the present invention is to provide the means toreduce the required length of runways for airplane takeoff, whilereducing the stress on the structure of the plane and saving fuel.

Another objective of the present invention is to provide RAR segmentsthat partially disabled airplanes may use for landing with greatlyincreased probability of coming to stop safely rather than, e.g.,sliding uncontrollably to a stop over great distances, which could meanleaving the runway and striking some obstacles or falling into a ditchor water. In addition, since the runway surface is readily accessiblefrom under the RAR surface panels, provisions can be made to introducehighly sticky and/or fire retardant or fire distinguishing substancessuch as fluid or foam to the surface of the runway or spray the samesome distance above the surface over the incoming vehicle tosignificantly reduce the probability of fire and/or introduce fireinhibiting gases so that the spilled fuel could not be ignited and/orprevent the fire from spreading.

In the remainder of this description, the basic principles of operationand various embodiments of the present invention are described in termsof airplanes and runways. However, it is understood that wheneverapplicable, the terms also apply to ground and other similar vehicles.

A basic principle of the operation of the reusable and adaptablerunaways (RAR) of the present invention is the provision for the vehicle(tires or some other structural member of a damaged aircraft) tocontinuously tend to climb an inclined surface, which under the weightof the vehicle undergoes a displacement thereby deforming certainelastic elements. The process is similar to the vehicle travelinguphill, and as the vehicle travels along the runway, its kinetic energyis stored in the deformed elastic elements. However, no significantamount of potential energy stored in the elastic elements is preferablytransferred back to the vehicle as it passes over the displaced surfaceof the RAR. To this end, appropriate means are preferably provided to“lock” the elastic elements in their deformed position, i.e., to “lock”the runway structure and its various members substantially in theirdeformed configuration.

Accordingly, a roadway upon which a vehicle travels is provided whichassists in decelerating the vehicle. The roadway comprises: a movablesurface extending in a direction of the vehicle's travel; and potentialenergy storage means operatively connected to the movable surface forconverting a kinetic energy of the vehicle into potential energy uponmovement of the movable surface thereby slowing the vehicle.

Also provided is a roadway upon which a wheeled vehicle travels whichassists in accelerating the vehicle. The roadway comprises: a movablesurface extending in a direction of the vehicle's travel; and potentialenergy transfer means operatively connected to the movable surface fortransferring a stored potential energy associated with the movablesurface into kinetic energy upon movement of the movable surface therebypropelling the vehicle.

Still provided is a method for slowing a vehicle upon a roadway. Themethod comprising: providing a movable surface upon which the vehicletravels; converting a kinetic energy of the vehicle into potentialenergy upon movement of the vehicle over the movable surface; andstoring the potential energy in the elastic elements of the movablesurface mechanism to thereby slow the vehicle.

Still provided is an RAR in which part or all of the kinetic energytransferred to the movable surface mechanism is absorbed by viscousdamping and/or dry friction forces and/or by controlling electric motorsand/or electric power generators.

Still yet further provided is a method for accelerating a vehicle upon aroadway. The method comprising: providing a movable surface upon whichthe vehicle travels; and moving the movable surface to transfer apotential energy stored in the movable surface to the vehicle to therebypropel the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus andmethods of the present invention will become better understood withregard to the following description, appended claims, and accompanyingdrawings where:

FIG. 1 illustrates a schematic sectional view of a preferredimplementation of a reusable and adaptive runway of the presentinvention.

FIG. 2 illustrates a schematic of a single runway panel and support andcontrol elements corresponding to the panel.

FIG. 3 illustrates a schematic of the single runway panel of FIG. 2under the weight of a vehicle tire.

FIG. 4 illustrates a schematic cross section of another preferredimplementation of the reusable and adaptive runway of the presentinvention.

FIG. 5 illustrates a schematic cross section of yet another preferredimplementation of the reusable and adaptive runway of the presentinvention.

FIG. 6 illustrates a schematic cross section of still another preferredimplementation of the reusable and adaptive runway of the presentinvention.

FIG. 7 illustrates a schematic cross section of another implementationof the reusable and adaptive runway of the present invention.

FIG. 8 illustrates a schematic cross section of still another preferredimplementation of the reusable and adaptive runway of the presentinvention.

FIG. 9 illustrates a graph showing a preferred relationship betweenspring displacement and force for the spring elements of the reusableand adaptive runway of the present invention.

FIG. 10 illustrates a schematic cross section of still another preferredimplementation of the reusable and adaptive runway of the presentinvention.

FIG. 11 illustrates a schematic cross section of still another preferredimplementation of the reusable and adaptive runway of the presentinvention.

FIG. 12 illustrates a schematic cross section of still yet anotherpreferred implementation of the reusable and adaptive runway of thepresent invention.

FIG. 13 illustrates a sectional view of a vehicle tire having means forconverting kinetic energy of the vehicle to potential energy, similar tothat of the RAR.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although this invention is applicable to numerous and various types ofroadways and surfaces, it has been found particularly useful in theenvironment of runways for aircraft. Therefore, without limiting theapplicability of the invention to runways for aircraft, the inventionwill be described in such environment. Those skilled in the art willappreciate that the RAR of the present invention can be used on roadwaysfor automobiles and trucks and for other wheeled vehicles. The RAR ofthe present invention can also be adapted for use with trains where thepanels described below are proximate the rails upon which the trainstravel.

A schematic of the side view of a preferred RAR illustrating its basicprinciples of operation is shown in FIG. 1. In this illustration, theRAR 100 segment is shown positioned at the end of a typical (fixed)runway 101. At the end of the fixed runway 101, one or more transitionrunway panels 102 are to be installed in a transition segment 103 of theRAR 100. The function of the transition segment 103 of the RAR 100 is toprovide for a smooth transition for a vehicle during its motion from thefixed segment of the runway 101 to the RAR segment 100. In general, morethan one transition runway panel 102 is preferred in order to make thevehicle motion smooth as it enters the RAR segment 100 of the runway,i.e., in order to prevent the tires from suddenly striking the RARsegment 100 which would otherwise form a step like configurationimmediately following the fixed runway segment 100.

The transition runway panels 102 are constructed with a surface panel102 which make an angle α (104 in. FIG. 1) with the surface of the fixedrunway 101, rising to the height H (105 in FIG. 1). Under the transitionrunway panel(s) 102 are elastic elements, motion constrainingmechanisms, braking mechanisms, and all other components, collectivelyshown in FIG. 1 as element 106, which hereinafter is referred to as therunway panel “support and control assembly.” The details of the supportand control assembly 106 is provided in FIG. 2. The support and controlassembly 106 is mounted on a runway foundation 107. Following thetransition runway panels 102, the regular runway panels 108 arepositioned. The runway panels 108 are held in place above the foundation107 by support and control elements 109, which are very similar infunction and construction to the support and control elements 106. InFIG. 1 and to simplify the illustration, the mechanisms used to attachthe transition panels 102 to the fixed runway 101 and to the othertransition 102 and regular runway panels 108 are not shown. Thesedetails are provided in the ensuing illustrations. In addition, it isunderstood that the outermost side of the runway panels 108 arepreferably not exposed. In practice, the sides of the runway panels 108are preferably protected from the elements without the addition of anymotion restraining elements such as with simple bellows. In addition, itis understood that in FIG. 1 only one runway panel 108 is shown alongthe width of each segment of the RAR 100. However, it is understood thatmore than one runway panel 108 may be positioned side by side along thewidth of each runway panel segment 108.

The structure of the simplest type of support and control elements 106and 109 is shown in the schematics of FIGS. 2 and 3. Such a support andcontrol element consists of one or more spring elements 110 and one ormore braking elements 111 connecting the runway panels 102 and 108 tothe runway foundation 107. As the vehicle tire 112 leaves the fixedportion of the runway 101, it first rolls over the panels 102 within thetransition segment 103 of the RAR 100, and then rolls over the regularRAR panels 108 as shown in FIG. 3. The relatively small angle α (104)ensures that the transition between the transition panel 102 and regularpanel 108 segments of the RAR 100 is relatively smooth. Depending on theweight W (114) being born on the tire 112 and the total spring rateprovided by the spring elements 110, the panel 102 (108) is displaceddownward a distance D (113) as shown in FIG. 3. The spring rate ispreferably selected, i.e., set by a spring rate adjustment mechanism(not shown) such that the amount of downward displacement D (113) isfairly close to the height H (105) of the regular panels 108. The amountof potential energy PE stored in the spring elements 110 is readilyshown to bePE=½k D²  (1)

where k is the effective spring rate of the spring elements 110,assuming that the spring elements 110 are not pre-loaded. If the springelements 110 are pre-loaded a distance D₀, then the potential energystored in the spring elements 110 is readily shown to bePE=½k(D+D ₀)²−½ k D ₀ ²  (2)

In general, the spring elements 110 are desired to be pre-loaded inorder to reduce the amount of displacement D for a desired level ofpotential energy PE.

The source of potential energy PE that is stored in the spring elements110 is the kinetic energy of the vehicle. Therefore, the kinetic energyof the vehicle is reduced by the amount of potential energy PE that isstored in the RAR panel 102 (108). Obviously, the panel 102 (108) andthereby the spring elements 110 have to be locked in their displacedposition shown in FIG. 3. Otherwise, as the tire 112 passes over thepanel 102 (108), the panel 102 (108) could transfer most of the storedpotential energy back to the tire, thereby causing the RAR system tohave a minimal effect in absorbing the kinetic energy of the vehicle,i.e., from slowing the vehicle down. Here, the locking action isintended to be provided by the brake 111, which is actuated by thebraking force 115.

The preferred length of each of the RAR panels 102 (108) relative to thesize of the tire 112 and the preferred methods of connecting the panels102 (108) together and to the runway foundation 107 will be describedlater.

The components shown in the support and control elements 106 and 109 arethe minimum type of elements that allow for the proper operation of theRAR 100. Additional elements, such as those previously mentioned may,however, be added to provide for features that may be desirabledepending on the operational requirements of each runway, the level ofautomation that is desired to be incorporated into the overall design,for allowing for the adjustment of one or more of the parameters of thesystem, its effective height H (105), the configuration of the system,etc. In the remainder of this description, various preferred designconfigurations and the types and ranges of parameters are provided as afunction of various desired operating conditions.

The operation of such reusable and adaptive runways (RAR) 100 isequivalent to the vehicle traveling along an inclined surface, therebytransforming its kinetic energy into potential energy proportional tothe vertical height that its center of mass attains. In the presentinvention, the kinetic energy of the vehicle is transformed intopotential energy stored in the deforming elastic elements, i.e., thesprings 110. In certain situations, it may be desired to providefriction (braking action) and/or viscous damping elements that arepositioned in parallel or in certain cases in series with the elasticelements, thereby dissipating a certain portion of the kinetic energy ofthe vehicle. Yet in other certain situations, it may be desired to usekinetic energy storage elements such as flywheels in series or inparallel with the elastic elements or even in place of the elasticelements. In a similar design, opposing magnet or magnets and coils(i.e., linear or rotary motors) may be used in parallel or in serieswith one or more of the aforementioned elements. Yet in certain othersituations, electrical energy generators may be positioned in series orparallel with the elastic elements or in place of the elastic elements,or in series or parallel with the kinetic energy storage elements or inplace of the kinetic energy storage elements. The electric energygenerators or electric actuation devices (or in fact any other means ofactuation) may be used as means to absorb part or the entire kineticenergy that is transferred to the RAR panels, or they may be used inpart or entirely as means of controlling the rate of such energytransfers. The latter means of control is usually aimed at achieving asmooth motion for the vehicle. In general, the spring rates, viscousdamping rates, and the characteristics of any one of the aforementionedelements may be constant or adjustable. Such means of adjustment of thecharacteristics and parameters of the aforementioned elements may beused to adjust the characteristics of the RAR 100 to their near optimalconditions for each approaching vehicle, its speed, and operatingcondition. The aforementioned elements may also have linear or nonlinearcharacteristics. The advantages and disadvantages of a number ofaforementioned combinations and the general characteristics that theycan provide the RAR system is described later in this disclosure.

In short, a number of combinations and configurations of one or moreelastic elements, one or more kinetic energy storage elements, one ormore viscous damping elements, one or more braking elements, one or moreelectrical or hydraulic or pneumatic motors or their combination, andone or more electrical energy generators may be positioned in series orin parallel to provide the desired effect of “absorbing” the kineticenergy of the vehicle.

The RAR panels 102 and 108 are preferably constructed with relativelyrigid but lightweight materials as relatively rigid but lightweightstructures. The surface of the panels are preferably coated withappropriately formulated material to enhance endurance, increasefriction and decrease wear.

The RAR surface panels 102 (108) may be constructed with panel or panellike elements that are relatively free to move relative to each other,particularly in the vertical direction and in rotation about atransversely directed axis (perpendicular to the vertical andlongitudinal axes of the runway or roadway). In such a configuration,the horizontal motion of the panels 108 relative to each other andrelative to the runway foundation 107 is preferably controlled byrelatively stiff elastic elements 125 (FIG. 4), preferably with aconsiderable amount of (preferably viscous like) damping (such as withsynthetic rubber type of materials) in order to control the panels fromslipping in the longitudinal direction under the rotating tire.Mechanical stops may also be provided to assist in the control of thehorizontal motion of the RAR panels 108. Such a RAR panel configurationis suitable when the size of the panels 108, particularly their length(measured along the length of the runway) is relatively small comparedto the size of the vehicle tire such that at any point in time, the tireis in contact with more than one panel 108, preferably with at leastthree panels 108. The latter condition is necessary in order to assure asmooth motion for the vehicle as the tire moves from one panel 108 tothe other, causing the panels 108 to generally conform to the shape ofthe tire as shown in FIG. 4, rather than causing the tire to move up astep like path.

In another embodiment of this invention, the surface panels 102 (108)are hinged together as shown in FIG. 5 along the length of the runway toallow for their relative rotation about their transverse axes in orderto accommodate to the shape of the traveling tire 112. The panels 108(or 102) are connected with hinges 120 to allow their relative rotation.Such a rotation is required for the smooth operation of the RAR so thatas the tire moves over the first panel 108 (FIG. 5) and depresses acertain amount, the next panel 108 is rotated counterclockwise therequired amount to allow such vertical displacement of the first panel108 without resulting in a step to be formed between the two panels 108.The hinge 120 or at its connections to the panels 108 or the panels 108themselves may be constructed with certain amount of flexibility toallow the change in the horizontal projection of the longitudinal lengthof the panels due to the relative rotation of the panels 108 to becompensated.

In yet another embodiment of the present invention, the panels areattached to the underlying structure (foundation 107) of the runway bymeans of mechanical elements, i.e., linkage or other types ofmechanisms, such that their motion relative to the foundation isconstrained in certain manner to allow for the smooth travel of the tireover the panels. An example of one of numerous possible types of suchmotion constraint mechanisms is shown in FIG. 6. This mechanism isconstructed with linkage type of mechanisms. In FIG. 6, the side view ofonly one runway panel 108 (102) is shown. In this design, one side ofthe panel 108 (102) is attached with two links 136 and 137 which arehinged together at the hinge 134. The link 136 is attached to the runwaypanel 108 (102) by the hinge 130. The link 137 is attached to the runwayfoundation 107 by the hinge 132. The opposite end of the panel 108 (102)is attached to the foundation 107 by links 138 and 139 which are hingedtogether with hinge 135. In turn, the link 138 is attached to the panel108 (102) by hinge 131 and link 139 is attached to the foundation 107 byhinge 133. The pair of links 136 and 137 and the pair of links 138 and139 reduce the total degree of freedom of the panel for motion in thevertical plane from three degrees of freedom (two displacements and onerotation) to two degrees of freedom, i.e., the motion of the panel inthe vertical plane is constrained by the linkage mechanism shown in FIG.6 to two degrees of freedom. As a result, other elements of themechanism 106 (109) (not shown in FIG. 6 for clarity), mostly the springelements 110, provide fewer constraining forces to provide for theaforementioned desired motion of the panels as the tire travels over thepanel. Those skilled in the art will appreciate that the elasticelements are operatively connected with the panels (or belt) to convertthe kinetic energy of the vehicle to potential energy. Thus, the elasticelements can be directly connected to the panels (or belt) or connectedto the links in way which deforms the elastic element(s) upon movementof the links.

It should be noted that in general, the panels 108 (102) are desired topossess two degrees of freedom in motion in the vertical plane. This isthe case since as the tire travels over the panels 108 (except a panel102 located immediately following the fixed segment of the runway), thepanels 108 are desired to undergo a motion which is essentially acounterclockwise rotation that brings their edge closest to the tiredownward, followed by a clockwise rotation that brings the opposite edgeof the panel downward until the panel is essentially horizontal. It isreadily observed that if the panels 108 are short relative to the sizeof the tire 112 as shown in FIG. 4, then during the abovecounterclockwise and clockwise rotations, the panels 108 would alsoundergo a vertical displacement such that the panels are essentiallytangent to the periphery of the tire 112 at all times. However, panels108 that are long relative to the size of the tire 112 such that thetire 112 may be located at times entirely over the surface of only onepanel 108, would undergo a more or less pure counterclockwise rotationas the leading edge of the panel 108 closest to the tire 112 is pusheddownward to essentially the maximum set depth 105, and as the tire 112moves over the panel 108, the panel 108 would then begin to rotateclockwise about the same leading edge until the panel 108 is essentiallyhorizontal. The configuration of the panels 102 (108) is shown by way ofexample only and not to limit the scope or spirit of the presentinvention. For example, as shown in FIG. 12, all or a significantportion of the panels can be arranged at an angle a such as thetransition panel 102, or alternatively, all of the panels could bearranged flat (e.g., α=0), such as panels 108. In the alternativeconfiguration of FIG. 12, the panels 102 are not attached to each otherbut are instead all hinged to the roadway for pivotal movementtherewith.

Another class of mechanism that may be used to constrain the motion ofthe aforementioned longer runway panels 108 (102) relative to the runwayfoundation 107 to the aforementioned sequential counterclockwise andclockwise rotation about the leading edge 140 closest to the incomingtire 112, as shown in FIG. 7. In this class of constraining mechanisms,the motion of the leading edge 140 of the panel 108 is constrained to avertical motion, while the panel 108 (102) is free to rotate about theleading edge 140. In the mechanism shown in FIG. 7, the motion of theedge 140 is constrained to the vertical direction by the sliding joint141, which consists of the sliding element 143 and the guide 144. Thesliding element 143 is hinged to the edge 140 of the panel 108 (102) bya rotary joint 142, thereby allowing the panel to rotatecounterclockwise as the edge 140 is pushed down to the previous paneland once the tire 112 begins to move over the panel 108 (102) shown inFIG. 7, to allow the panel 108 to rotate in the clockwise directionuntil it is essentially horizontal and depressed a distance H 105. Aplurality of such motion constraint mechanisms may be constructed. Infact, the mechanism shown in FIG. 7 is selected only for the purpose ofdemonstrating the mode of operation of such motion constraint mechanismsand does not constitute the preferred embodiment unless the slidingjoint is constructed as a living joint. This is the case since slidingjoints constructed sliding and guiding elements, even together withballs or rollers or other anti-friction constructions, are much moresusceptible to sticking, generally generate more friction forces, areharder to keep free of dirt and contaminants, and are generally largerand heavier, thereby are generally desirable to be avoided. Thepreferred mechanisms are constructed with rotary joints, such as in theform of one of many well-known linkage mechanisms that generate nearlystraight-line motions.

Motion constraining mechanisms may also be preferably used to constrainthe motion of the panels 108 (102) to rotations about axes perpendicularto the longitudinal and vertical directions, i.e., clockwise andcounterclockwise rotations as illustrated in FIGS. 4, 5, 6, and 7. Inthe schematic of FIG. 8, the edge 150 of a runway panel 108 (102) alongthe width of the runway 107, i.e., as viewed in a direction parallel tothe longitudinal direction of the runway, is illustrated. To limit themotion of the runway panel to the above rotations, the motionconstraining mechanism constrains the edge 150 to motions in thevertical direction while keeping the edge 150 parallel to the horizontalplane (here, for the sake of simplicity and without intending to placeany limitation on the design of the runway foundation, the foundationsurface is considered to be flat and parallel to the horizontal plane).The simplest linkage mechanism that would provide the above constrainingmotion, is a double parallelogram mechanism 160 as shown in FIG. 8. Themechanism consists of links 153 of equal lengths that are attached tothe runway panel 108 (102) by spherical joints 151; links 155 of equallengths that are connected to the foundation 107 with spherical joints156; and a common link 154 to which the ends of the links 153 and 155are hinged with rotary joints 152. One or more double parallelogrammechanisms 160 may be used to constrain the motion of each runway panel108 (102).

In yet another embodiment of the present invention as shown in FIG. 10,the panels are replaced with-an appropriately sized and relatively flatsurfaced chain like or belt like structures 170 that cover a commonlyused underlying support structure which is in turn attached to thesupport and control elements 106 (109) with or without one or more ofthe aforementioned motion constraining mechanisms. The use of such chainor belt like surface structures allow for a smoother travel of the tire,similar to the case of shorter panels shown in FIG. 4. For example, acontinuous belt segment would in effect act similar to panels with verysmall lengths.

Hereinafter, the above types of runway surface elements are referred toas runway panels without intending to limit them to any one of the abovedesigns. To those skilled in the art, numerous other “runway panel”design configurations that allow relatively smooth vertical displacementof the underlying surface as the vehicle tire travels over such “runwaypanel” and thereby affect deformation of appropriately positionedelastic potential energy storage elements similar to the spring elements110 are possible and are intended to be covered by the presentdisclosure.

The runway panels are elastically supported by spring elements that arepositioned between the panels and the runway foundation. The elastic(spring) elements may take any form, for example, they may beconstructed in a helical or similar form by spring wires of variouscross-sections, or they may be formed as torsion or bending springs,torsion bars, or any of their combinations. To optimally control thevertical movement of the runway panels, the spring rates, i.e., therelationship between the applied vertical force and the resultingvertical displacement of the runway panel may be linear or nonlinear.The spring elements may be positioned directly between the runway panelsand the runway foundation or act on the mechanical elements that providemotion constraint to the panels. In general, various spring types andconfigurations may be used to provide various elastic responses upon theapplication of load (mostly vertical) at certain points on the panel,i.e., to provide the desired effective spring rates in response to thevertical displacement and rotation about an axis directed in thetransverse direction.

The potential energy storage elements can also be the structuralelements disclosed in U.S. Pat. No. 6,054,197, the contents of which areincorporated herein by its reference. In general, as shown in FIG. 11,the weight 115 of the tire 112 deforms the structural element 200 whichis disposed between each panel 102 (108) and the runway base 107 tostore a potential energy therein. The structural element may also itselfserve as the braking element where displaced fluid 202 from the interiorof the structural element (caused by the deformation) is captured in areservoir 204 and restricted from returning to the cavity 202, such asby closing a valve 206 while the structural element is deformed. Thestructural element 200 is released or reset (extended) by removing therestriction, such as by opening the valve 206 to allow the fluid to flowback into the cavity 202. Preferably, the structural elements 200 areremotely controlled by a processor 208 operatively connected to asolenoid which operates the opening and closing of the valves 206. Theamount of deformation the structural elements undergo can also becontrolled and varied by the processor by controlling the amount thatthe valves 206 open (i.e., the orifice size is varied). A structuralelement 200 corresponding to a valve 206 that is partially opened willbe more rigid and thus undergo less deformation than a structuralelement having a corresponding valve 206 that is fully open.

Each runway panel assembly, i.e., the runway panel, its motionconstraining mechanisms and the elastic elements, viscous and dryfriction based damping elements, are also equipped with one-way locks,that as the elastic elements are deformed under load, they are held intheir maximum deformed position and are substantially prevented fromregaining their original configuration as the load is lifted. Suchone-way locking mechanisms may be placed at any appropriate positionbetween the runway panels and the foundation or between the runwaypanels and the mechanical motion constraining elements. The one-waylocking mechanisms may also be positioned in parallel with one or moreof the elastic elements, or may be constructed as an integral part ofone or more of the elastic or damping elements. Regardless of theirdesign and the method of integrating them into the runway panelassembly, the one-way locks serve one basic function. This basicfunction is to “lock” the depressed runway panels in place and preventthem from “springing” back to their original position. In other words,as the airplane or other vehicle tire displaces a runway panel, the workdone by the force exerted on the displacing surface panels (mostlyvertically and some in rotation) is to be stored in the spring elements110 (200) as potential energy. The function of the aforementionedone-way lock mechanisms is to “lock in” this potential energy bypreventing the spring elements 110 (200) from moving back to theiroriginal position. The potential energy stored in the spring elements110 (200), neglecting all other commonly present energy losses due tofriction, etc., is equal to the kinetic energy that is transferred fromthe airplane or other vehicle to the spring elements 110 (200). Ingeneral, one or more elastic elements of various types may be used oneach runway panel and one or more of the spring elements may beinitially preloaded. The primary purpose of preloading of the elasticelements is to reduce the amount of vertical and/or rotationaldisplacement of the runway panels for a given applied load. Anotherfunction of selectively preloading one or more of the elastic elementsis to create the load-displacement (rotation) characteristics that isoptimal or close to optimal for the operation of the runway.

In the preferred embodiment of this invention, the effective springrates of each runway panel assembly and the spring preloading areadjustable remotely. The spring rates and preloads may obviously beadjustable manually, particularly for runways that are only used with afew similar types of airplanes.

In general, the runway panel assemblies are designed such that they donot require motion damping elements such as viscous dampers for theirproper operation such as to prevent the bouncing action upon initialtire contact. Such dampers are used to control the response of therunway panel assemblies to the speed of application of the tire load. Inany case, minimal damping is desired to be used to make the RAR mostresponsive to high-speed vehicles. In addition, if the stored potentialenergy in the elastic elements are intended to be used or harvested,minimal damping is desired to be employed since such dampers wouldconvert a portion of the kinetic energy of the plane into heat, i.e., atype of energy that is difficult to harness as compared to potentialenergy stored in elastic elements.

On the other hand, certain runway panel assemblies, particularly thosethat are located at or close to the portion of the runway over which theplane travels at high speeds, may be desired to be equipped with motiondamping elements such as viscous dampers that are appropriatelypositioned to provide resistance to the displacement and/or rotation ofthe runway panels for smooth operation. The effective damping rates ofthese elements are also desired to be adjustable remotely, manually andif possible by a closed-loop control loop.

When the runway is intended to slow down airplanes upon landing, theplane may first land on a regular (fixed) runway segment and then enterthe RAR segment to be slowed or be brought to complete stop. In suchcases, it is important that the transition between the two runwaysegments be as smooth as possible. Such smooth transitions are readilyobtained, e.g., by providing higher spring rates for the initial highwaypanels and/or hinging them to the edge of the regular runway segment andthen gradually decreasing the panel spring rates to achieve maximumdeflection, i.e., maximum vertical displacement of the runway panelsunder tire load. As the result, the vehicle begins to slow down smoothlyas it enters the RAR segment. Then, as the plane continues to travelalong the RAR segment, the runway panels begin to be displacedvertically to their maximum set amount, and the kinetic energy of theplane continues to be transferred to the spring elements, while acertain (usually much smaller) portion of the kinetic energy isdissipated in the viscous damping and/or brake like friction elements.The plane will loose no control since the slowing down process does notinvolve any skidding or reduction or loss of contact friction betweenthe tires and the runway surface. This is in total contrast withsand-filled roads and collapsible concrete runways that would formcertain “pathways” along which the tires are forced to travel. Ofcourse, the RAR may also constitute the entire runway which may be muchsmaller in length then a conventional runway for the same size aircraft.

Once the plane has been slowed down to the desired speed or has beenbrought to rest, the braking mechanisms of the runway panels can bereleased to slowly bring the panels to their original position. To makethe movement smooth and prevent vibration, viscous damping or frictionelements may be engaged during this return movement. Alternatively,energy transformation means such as electric generators may be used totransform the stored energy in the elastic elements into usable electricenergy.

On the other hand, the potential energy stored in the elastic element ofthe runway panels may be used to accelerate a plane during its takeoff.The process is the reverse of the slowing down process. Here, as thetire moves over a depressed runway panel, the panel brakes are releasedin a controlled manner from the back of each panel to the front as thetire moves over the panel, thereby pushing the plane forward andtransferring the potential energy stored in the elastic elements to theplane as kinetic energy. By properly releasing the braking mechanisms,it is possible to transfer most of the stored potential energy to theplane. This process has the effect of allowing the plane to travel alonga runway with a downward incline, thereby transferring the potentialenergy of the plane due to the total drop in the plane elevation to theplane in the form of kinetic energy.

Both landing and taking off processes using RAR can be seen to be highlyenergy efficient. During the landing, minimal or no braking is required.During takeoff, a large portion of the required kinetic energy can beabsorbed from the RAR. By appropriate selection of the RAR parameters,planes are able to land and take off in relatively short runways. Suchrunways can therefore be also very useful for the construction ofemergency landing and takeoff strips and for aircraft carrier.

In general, elastomeric or hydraulic type of shock absorbers and bumpersmay be used to limit the motion of the runway panels 108 (102) in thevertical direction to the designated depth H (105), or prevent excessivelateral motion of the panels or the motion constraint mechanisms, etc.In all situations, such elements are provided in order to smoothly bringthese components to a stop and without a sudden shock. For the case ofthe depth 105 limiting stops, the allowable depth H (105) is preferablyadjustable by a control system that adjusts the system parameters foreach particular vehicle and initial speed and operating condition. Sucha controller is described above with regard to FIG. 11, however, similarcontrol methods may be employed in the other embodiments discussedherein for controlling any or all system parameters.

In general, the spring elements 110 are preferably preloaded to reducethe required depth H (105). It is also generally preferable to havesprings with nonlinear force displacement characteristics of the generalform shown in FIG. 9 so that as the deformation is increased, theeffective spring rate is also increased. Such a spring ratecharacteristic allows the springs to also act as effective stops as themaximum desired depth H (105) is approached. The general shape of thedesired spring displacement versus spring force curve 163 is shown inFIG. 9. The amount of preloading force is indicated by 165. The springrate, i.e., the slope of the curve 163 increases with springdisplacement. For a given displacement 161 of the spring, thecorresponding spring rate k (162) is given by the slope of the tangent164 at that point on the curve 163. As can be observed, by properselection of the spring 110, as the displacement is increased (in thiscase as it reaches the desired amount H (105), the spring rate becomesvery large (somewhere to the right of the point 161), where the springturns into an effective stop.

In general, more than one wide runway panel 108 (102) is desired tocover the width of the runway. By utilizing narrower panels, theeffective mass that is displaced as the tire moves over a panel isreduced, thereby allowing for the RAR panels to respond quickly. As aresult, faster moving vehicles can be accommodated. In which case, thepanels are desired to be hinged together as described for thelongitudinal sides of the panels, together with similar elastic elementsto allow the length variations due to the relative rotation of thepanels. In one embodiment of the present invention, the aforementionedrelative rotation of the panels along their hinged side edges isallowed. Such an option would provide a certain amount of barrier thatthe tires have to climb in order to move in the direction of the widthof the runway. Such a barrier is desired, particularly if the vehicle isdamaged or if the pilot is having problems controlling the vehicle. Inan emergency situation, by allowing the depth H (105) to become larger,a larger stabilizing barrier can be provided for keeping the vehicle onthe runway. For such emergency situations, auxiliary barriers positionedon the sides of the runway may also be activated to increase the heightof the side barriers. On the other hand, in normal situations, theaforementioned relative rotation of the panels is preferably limited oris totally prevented by the provided hinges and the motion constrainingmechanisms.

Although the RAR is described above having static parameters, suchparameters can be variable, either adjusted manually or automatically inresponse to sensed characteristics. For Example, the RAR can be equippedwith sensors for detection of the position, size, and/or velocity of thevehicle before entering the RAR. The information detected by one or moresensors is then input to a processor, which adjusts the parameters ofthe RAR before the vehicle enters the RAR. The sensors can also continueto monitor the vehicle as it travels on the RAR and adjust theparameters thereof accordingly. For example, one parameter that can beadjusted based on the sensed characteristics is the spring rates of thespring elements 110. Means for adjusting spring rates of spring elementsare well known in the art, such as helical or other passive springs incombination with pressurized gas springs. Another example of a parameterthat can be adjusted, is the viscous damping rates of the damper canalso be adjusted based on the sensed characteristics. Means foradjusting damping rates are well known in the art, such as providing anelectrically actuated orifice change or by using magneto-restrictivefluids in fixed orifice fluid dampers. Yet another example of aparameter that could be adjusted in response to the sensedcharacteristics is to provide moving stops that vary the amount ofmovement of the panels 102, 108. The stops can be moved by any meansknown in the art, such as by using electrically or hydraulically drivenlead screws. These characteristics can be varied as a whole (applied toall of the panels 102, 108, or applied to selective panels 102 (108) anddone manually or under the control of a central processor or controlunit.

Referring now to FIG. 13, there is shown a tire 300 capable oftransferring the kinetic energy of a vehicle to potential energy thusslowing the vehicle as if it were going up an inclined surface. The tire300 has support and control assemblies 109 similar to that describedabove with regard to the RAR. Those skilled in the art will appreciatethat as the tire 300 rotates, the elastic elements contained in thesupport and control assemblies 109 are deformed and held in the deformedstate (such as with a braking element) similar to that described abovewith regard to the RAR. As the tire 300 further rotates such that thedeformed elastic elements are no longer in contact with the roadway (orrunway) 101, the braking of the deformed elastic elements is releasedand the process repeats as the tire continues to roll over the roadway101. Those skilled in the art will appreciate that such a tire, whenactivated, slows the vehicle as if the vehicle was traveling up aninclined surface. Those skilled in the art will further appreciate thatthe tire can also be used to accelerate the vehicle. When the tire 300is used during normal operation the elastic elements are either notengaged so as not to deform or permitted to freely deform without beingheld in the deformed state.

While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

1. A roadway upon which a vehicle travels, the roadway comprising: amovable surface extending in a direction of the vehicle's travel; andpotential energy storage means operatively connected to the movablesurface for converting a kinetic energy of the vehicle into potentialenergy upon movement of the movable surface thereby slowing the vehicle;wherein the potential energy storage means comprises: one or more springelements operatively connected to the movable surface such that movementof the movable surface deforms the one or more spring elements into adeformed state to store potential energy therein; and one or morebraking elements for maintaining the one or more spring elements in thedeformed state such that the stored potential energy in the one or morespring elements is not substantially transferred back to the vehicle. 2.The roadway of claim 1, wherein the movable surface comprises aplurality of movable panels.
 3. The roadway of claim 2, wherein theplurality of movable panels comprises: one or more transition panelslocated at a portion of the movable surface first encountered by thevehicle, the one or more transition panels being angled with respect toa fixed surface; and horizontal panels substantially having no anglewith respect to the fixed surface.
 4. The roadway of claim 3, furthercomprising a linking element disposed between adjacent panels in theplurality of movable panels for linking the adjacent panels togetherwhile permitting relative motion between the adjacent panels.
 5. Theroadway of claim 4, wherein the linking element comprises one or moreelastic elements connected at opposite ends of the adjacent panels. 6.The roadway of claim 4, wherein the linking element comprises one ormore hinges connected at opposite ends of the adjacent panels.
 7. Theroadway of claim 1, wherein the movable surface comprises one or moreflexible contiguous belts.
 8. The roadway of claim 1, wherein the one ormore spring elements are compression springs.
 9. The roadway of claim 1,further comprising means for remotely controlling a characteristic ofthe one or more spring elements.
 10. The roadway of claim 1, wherein theone or more braking elements are mechanical brakes actuated by a brakingforce.
 11. The roadway of claim 1, further comprising means for remotelycontrolling the one or more braking elements to selectively maintain andrelease the one or more spring elements in and from its deformed state.12. The roadway of claim 1, further comprising a motion constraint meansfor constraining a movement of the movable surface in at least onedegree of freedom.
 13. The roadway of claim 12, wherein the motionconstraint means is a mechanical linkage.
 14. The roadway of claim 1,wherein the vehicle is an aircraft and the movable surface is at least aportion of a runway.
 15. A method for slowing a vehicle upon a roadway,the method comprising: providing a movable surface upon which thevehicle travels; converting a kinetic energy of the vehicle intopotential energy upon movement of the vehicle over the movable surface;and storing the potential energy in the movable surface to thereby slowthe vehicle; wherein the converting comprises deforming one or morespring elements operatively connected to the movable surface into adeformed state and wherein the storing comprises maintaining the one ormore spring elements in the deformed state such that the storedpotential energy in the one or more spring elements is not substantiallytransferred back to the vehicle.